Tone Stack Straight Into EL84...

[quote author="RogerFoote"]That's good to hear! With this in mind I am going to persue the experimentation before I cut holes for power tubes.[/quote]

Amen to that! And a very HAPPT NEW YEAR TO ALL AT PRODIGY PRO FORUMS!!!! ;-)

sc

[quote author="Swedish Chef"]I think I need to "doo the math" on the Fender tone stack as the PRR comment rings so true in my practical experience. On the little 7watter that I'm fooling around with at the mo' I started with just a "High" roll off and it sounded very honky, and not very appealing at all, but as soon as I began to elaborate the tone circuitry the sound started to become much more pleasing. After messing about with quite a number of different combinations I ended up with the Leo Classic. It makes sense really, as he had a few units/ years to get it right. It's just so flexible, and yes, perhaps there are other stacks that are better for specific tasks but as a jack-of-all-trades it does VERY well for my tastes.

Stephen: My 7W single EL84 through a 1x12 Celestion Blue (100dB sens) stands up pretty well to my drummer and yes, the tone does make a diffference ;-)

sc[/quote]

Just turn of the year joking! I'm amazed that 7 watts is sufficient to stand up to a drummer. How much more perceived loudness would there be between 7 watts and say 30 watts, assuming properly matched speakers with greatest efficiency?
Stephen

All of this is still slightly fuzzy around the edges to me but as far as I understand it it runs approx. thus:

A percieved doubling of loudness is equivalent to a 6dB increase.

Doubling the power of an amp will give you an increase of volume of just 3dB, which due to the logarithmic nature of dB is all but imperceptible and certainly a long way off doubling in percieved loudness.

To get double the percieved loud, from the above, I guess you need 4 times the power( 3dB + 3dB).

That's correct, right? OR am I totally off beam?

So to double the perceived volume of my 7W through the same speaker (which incidentally is only rated at 15W) you'd need about 30W, I guess.

The thing is, with my 100dB efficiency speaker I am already twice as loud as the same amp through a speaker with 94dB efficiency:green:

Tell me I'm right...please.

sc

Chef.

I could be wrong*, but I believe that to perceive a doubling of volume requires an increase of one Bell. That is a 10 db (deci-bell) increase. To increase the signal by 10 db is about 10*the power. To be twice as loud as a 15 watt amp would require a 150 watt amp given the same speaker etc.etc..


* I am human so can and will be wrong on ocassion. :green:

Peace - Out
Irv

> I believe that to perceive a doubling of volume requires an increase of one Bell.

No. The Bel is just a 10X increase of Power. Mainly a convenient math function.

By pure coincidence, the smallest audible change in a pure steady tone is about 0.1 Bel (1dB). Set up a signal generator with a moderate pitch and moderate volume. Ask your friend to turn the level up or down slowly. Stop when you are sure you hear a change. The result will be all over the place, but for most people it averages about 1dB, mid-band and mid-level.

0.602 Bels (6.02 deciBels) is 4 times the power, which happens when pressure (voltage or sound) doubles. (Twice the voltage causes twice the current, 2V*2I= 4 times the power.)

We don't have numbers in our ears, and "twice" is not a clear concept, but many people will accept ~6dB as "twice/half as loud", for soft and medium tones.

BUT. At high levels, a little muscle in your ear tenses-up, reduces the transfer from air to inner-ear, to protect your hair-cells. Music is often played near this level. Rock drummers always play in this range. It is easy to get into the ear-tensing volume range, small amps will do it. So when you ask "how much MORE power do I need", you are almost always working against the ear-tensing muscle, and 6.02dB is not "twice as loud". Air pressure goes up 6dB, your ear muscle tenses-up and adds 1dB to 4dB loss, your ear-hair-cells feel a 5dB to 2dB change.

The big-amp companies love the "10dB for twice as loud" approximation, because it sells bigger amps. At sane hi-fi volumes, 7dB to 8dB is probably a better number. At live-rock volumes, 8dB to 10dB is probably a good guide.

7 Watts to 30 Watts is 6.3dB. Assuming they are the same-sounding watts (distortion flavor has a LOT to do with how loud a Watt is), then from down the street where it is only medium loudness, it will be almost twice as loud. Up close to a 7 Watt instrument amp with hot speaker, levels are near 100dB SPL and your ear-muscle is working hard. Going to 30 Watts may be about 1.5 times as loud.

And a 7 Watt single-ended amp can be pushed to 14+ Watt peaks with 50+% sweet distortion. A 30 Watt is usually push-pull, so in overdrive the distortion rises fast and not sweetly. The difference in timbre is more impressive than the difference in level.

Thanks so much PRR!
Once again you have cleared the murky waters...

sc :green: